Notching press

ABSTRACT

A NOTCHING PRESS FOR PRODUCING STACKS OF LAMINATION FOR CONICAL ARMATURE MOTORS WHEREIN A PUNCHING TOOL IS DISPLACED RADICALLY RELATED TO THE AXIS OF A SADDLE STOCK SHAFT ADAPTED TO RECEIVE A SHEET METAL BLANK, AND MEANS IS PROVIDED FOR EFFECTING INCREMENTAL RADIAL DISPLACEMENT OF THE SADDLE STOCK SHAFT RELATIVE TO THE TOOL, WHEREIN THE INCREMENTAL DISPLACEMENT MEANS IS OPERABLE TO PRODUCE ANY ONE OF A PLURALITY OF DIFFERENT DISPLACEMENT INCREMENTS AND A PROGRAMMING DEVICE IS PROVIDED OPERATIVE   TO DETERMINE A SEQUENCE IN WHICH SAID INCREMENTAL DISPLACEMENTS ARE SELECTED, THE PROGRAMMING DEVICE BEING PROGRAMMABLE IN DEPENDENCE OF THE NUMBER OF BLANKS REQUIRED TO FORM A LAMINATION STACK OF THE REQUIRED DIMENSIONS.

NOV. 30, 1971 SCHNEHDER ETAL 3,623,385

NOTCHING PRESS Filed Dec. 11, 1969 6 Sheets-Sheet l BY 4 W 14am; 0' M11 NOV. 30, 1971 SCHNEIDER ETAL 3,623,385

NOTCHING PRESS Filed Dec. 11, 1969 6 Sheets-Sheet 2 Fig.3

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NOTCHING PRESS Filed Dec. 11. 1969 6 Sheets-Sheet 6 Fig. 10

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By OTTO KlAlQIw United States Patent US. Cl. 83-71 16 Claims ABSTRACT OF THE DISCLOSURE A notching press for producing stacks of lamination for conical armature motors wherein a punching tool is displaced radically related to the axis of a saddle stock shaft adapted to receive a sheet metal blank, and means is provided for effecting incremental radial displacement of the saddle stock shaft relative to the tool, wherein the incremental displacement means is operable to produce any one of a plurality of different displacement increments and a programming device is provided operative to determine a sequence in which said incremental displacements are selected, the programming device being programmable in dependence on the number of blanks required to form a lamination stack of the required dimensions.

This invention relates to a notching press for producing stacks of laminations for conical armature motors, of the type having a saddle stock shaft which serves to receive a sheet metal blank, and a punching tool, the radial distance between the saddle stock shaft and the punching tool being adjustable by means of an incremental drive.

=.In conical armature motors the stack of laminations forming the armature has the form of a truncated cone, and the motor stator has a bore of complementary shape. Those laminations situated in mutually corresponding positions in the stator and rotor lamination stacks are punched from a common blank. For each blank, in a known punching procedure, the stator slots are first punched out by successive cuts made by a first press, then in another press the rotor lamination is cut out of the stator lamination, likewise with successive single cuts (in some notching plants these two operations are carried out simultaneously in the same machine) and then another press cuts the slots in the rotor lamination. Other sequences of punching operations are however possible. The diameter of the rings of notches and of the dividing out between the stator and the rotor lamination must vary according to the position the laminations occupy in the stack. This is achieved by displacing the saddle stock shaft, which carries the blanks to be punched and about the axis of which the blanks are turned during the machining, radially relative to the tool as successive laminations in a single stack are punched. Difficulties arise however since, for a lamination stack of a given height, the number of laminations in the stack may vary considerably as a result of the inevitable tolerances in the thickness of the laminations. It is therefore not possible for the saddle stock shaft to be displaced, by an iden tical increment between the punching of successive laminations, since this increment will be dependent on the number of sheets in the stack of laminations being machined.

Radial movement of the saddle stock shaft is in practice produced by a ratchet gear driven by a pawl, and it is consequently not possible to provide a continuously variable increment. The expedient has been adopted ice therefore in known machines of adjusting the feed increment to a level appropriate to stacks having the minimum number of laminations found in practice, that is to say, the maximum feed increment required in practice is adopted. When stacks containing a larger number of laminations are to be machined, the drive of the saddle stock shaft is disengaged every time a predetermined number of laminations have been punched, so as to omit one drive increment, and thus the shape of the cone produced by successive laminations is made to conform aprpoximately to that desired. The disconnection of the drive to the saddle stock shaft is either effected manually by the operator of the press or by means of a preset counter. The method has the serious disadvantage that very pronounced irregularity of the internal profile of the stator lamination stack and of the external profile of the rotor lamination stack occurs.

After punching and stacking, the stacks of laminations are subjected to a grinding treatment, which produces the final conical surfaces. For economy in the grinding process, it is desirable that the counter of the punched lamination stacks should conform as closely as possible to an exact conical form, since otherwise not only will the amount of grinding work be excessive but in addition if a prescribed air gap is to be maintained between the rotor and the stator in the finished motor the rotor will have to be displaced axially in relation to the stator or, if the rotor and stator of the motor are axially aligned with one another the air gap will be enlarged. In the first case the end laminations of the stator at one end and of the rotor at the other end will not be utilised magnetically, and in the second case the magnetic resistance of the magnetic circuit formed by the rotor and stator will be increased.

The object of the invention is to overcome the disadvantages of such known notching presses in the machining of lamination stacks for conical armature motors so as to provide lamination stacks whose contours come closer to the desired final contour after grinding.

According to the invention there is provided a notching press for producing stacks of laminations for conical armature motors, comprising a saddle strock shaft adapted to receive a sheet metal blank, a punching tool displaced radially relative to the axis of the saddle stock shaft, and means providing incremental radial displacement of the saddle stock shaft relative to the tool, wherein the incremental displacement means is operable to produce any one of a plurality of different displacement increments and a programming deivce is provided operative to determine a sequence in which said incremental displacements are selected, the programming device being programmable in dependence on the number of blanks required to form a lamination stack of the required dimensions.

The advantage of the invention is that for lamination stacks of given dimensions it is possible to achieve a close approximation to the desired conical contours with stacks containing varying numbers of laminations, thus minimizing the grinding required to produce the desired smooth conical surfaces. In addition, it is possible for the air gap between rotor and stator also to be maintained within narrow limits without axial displacements of the stator relatiev to the rotor, which would result in magnetic non-utilisation of certain stator and rotor laminations, being necessary. Another advantage is that a notching press constructed in accordance with the invention can be constructed to provide good operational reliability, since relatively few control elements are required and for these it is possible to use tried and tested components.

In one embodiment of the invention the programming means includes a store in which various programmes are stored in such a manner as to permit selection. A store of this type may for example be a punched tape, a stack of punched cards, a magnetic core store, a coding switch or a template.

For the purpose of adjusting the radial displacement of the saddle stock shaft relative to the punching tool it is possible to use an electric stepping motor the drive increment of which is selected by selecting the number of pulses fed. In a preferred embodiment of the invention, however, a stepping mechanism is used since such a mechanism can be made very robust and can therefore itself take over the drive of the saddle stock shaft, and in addition can be made to work very accurately.

The stepping mechanism may for example be in the form of a rack or frictional ratchet mechanism. In a preferred form of construction however the stepping mechanism is in the form of a pawl driven ratchet wheel mechanism. By suitable selection of the diameter of the ratchet wheel, the pitch of the ratchet wheel teeth, and the stroke of the pawl it is possible to provide practically any desired sequence of incremental displacements of the saddle stock shaft and to make such sequences accurately reproducible.

For the purpose of driving the pawl there may be provided a telescopic actuator device the stroke of which is adjustable, for example by selectively engageable or stepped stops, whereby to enable the stroke of the pawl and hence the incremental dispalcement of the saddle stock shaft to be varied. In a preferred embodiment however the pawl is drivingly connected to a link pivotally connected, at points spaced from each other and the point of connection to the drive of the pawl to the movable elements of two telescopic actuators, and the programming device is operative selectively to control the actuators for simultaneous or alternative operation. The actuators may be for example solenoids or fluid operated rams. In this arrangement the pawl may for example be driven from the centre of the link, the two actuators having different stroke lengths. By alternative or combined operation of the two actuators it is thus possible to select three difierent displacement increments, namely a small increment by operating only the actuator with the shorter stroke, a medium increment by operation only the actuator with the longer stroke, and a large increment by operating both actuators together.

In one embodiment of the invention however, the two actuators both have the same stroke lengths, but the spacing of the connection points between the link and the actuators and the drive to the pawl is such that the effective lever arm formed by the link in relation to the pawl drive is greater relative to one actuator than relative to the other. It is thus possible to obtain three different incremental displacements of the saddle stock shaft by selective operation of the actuators even when they have the same stroke.

The programming means for selection of the sequence of displacement increments of the saddle stock shaft may take a wide range of forms. For example, it may comprise a ring counter having a counting cycle of preselectable length and producing an output signal on completion of each counting cycle, means generating a given number of pulses for each cycle of the press and applying them to the ring counter, and means operative to select a dilferent displacement increment to be carried out by the displacement means on receipt of an output signal from the ring counter. In this case the press is set so that a medium displacement increment occurs when no output signal comes from the ring counter. When such an output signal does occur, the programming means then supplies either a signal which selects the small increment or a signal which selects the large increment. If all the laminations of the stack are of equal thickness, then only either the large or the small increment will be selected, so that the sequence of increments will either comprise medium increments with periodic large increments, or medium increments with periodic small increments according to whether the stack contains a smaller or larger number of laminations than a stack which would be correctly punched using medium increments only. Thus, depending on the number of laminations in a stack, either a continuous sequence of medium increments may in fact accurately provide the desired cone profiles, in which case no correction is necessary, or the medium increments may result in cone profiles which are too acute or too obtuse, in which case periodic large or small (but not both) increments must be introduced for the purpose of correction.

In one embodiment of the invention the pulse generator comprises a signal generator, a counter set to count a preselected number of cycles from the signal generator in response to each cycle of the press, and a gate circuit cut ting off the output of the signal generator in response to said counter completing its count. It is however also possible for the pulse generator provided to be a perforated disc driven in rhythm with the machine and associated with photoelectric sensing means, or a toothed gear associated with a pick up coil in which a voltage impulse is induced for each tooth.

The main advantage of this arrangement is that finer control can be obtained by increasing the number of pulses produced for each cycle of the press, since with a large number of pulses fed to a ring counter having a correspondingly lengthened counting cycle, very fine adjustments may be obtained enabling the closest possible adherence to an ideal profile for the finished lamination stacks. Thus with a ring counter having a two figure count cycle it is for example possible to use a pulse/count cycle ratio of 29:30 and 28:29, but with a single-figure count cycle only such ratios as 2:3 or 3:4. In one embodiment of the invention it is possible for the number of pulses required by the ring counter for one complete cycle to be manually selected. The number selected depends firstly on the number of pulses fed to the ring counter by the pulse generator per press cycle and, for a given stack height and a given cone angle, on the number of laminations contained in the stack to be machined. The number of pulses applied by the notching press per machine cycle is preferably predetermined and the length of the ring counter cycle is adjusted in dependence on the number of laminations according to a table, which at the same time indicates whether the larger or the small displacement increment should be used for correction purposes. Such larger or smaller increments are applied each time the ring counter completes a cycle, the selection of the appropriate increment being carried out by setting, for example, an additional control at the same time as the length of the ring counter cycle is set, the position of the additional control determining whether the output from the ring counter causes a larger or smaller increment to be selected.

It is also posible for the ring counter to be constructed to count through a cycle of constant length and for the number of pulses supplied per machine cycle to be varied, for example by varying the period during which the gate circuit is open and permits the passage of pulses to the ring counter.

In another embodiment of the invention the ring counter is not adjusted manually, but the programme store incorporates a reading device which adjusts the cycle length of the ring counter in the desired manner. Adjustment appropriate to the number of laminations in the stack to be punched is then effected by selection of the corresponding programme in the store.

It is however not essential for the press to be provided with a ring counter and a pulse generator as programming means. In one embodiment of the invention the programme control provided comprises a wheel which is driven stepwise in synchronism with the press, means being provided transmitting a signal in response to the wheel reaching a predetermined angular position. In one such embodiment, the signal transmitting means comprise a switch in series with electrically operated means to select the appropriate displacement increment, the switch being controlled by a cam on said wheel, or the wheel is provided with an aperture or bore sensed by a stationary photoelectric cell and a stationary light source, the signal produced indicating that a large or small displacement increment is necessary. The stepping increments of the wheel may be made adjustable, this adjustment being effected in dependence on the number of laminations in a stack to be punched.

In one embodiment of the invention this wheel is a ratchet wheel associated with a variable stroke pawl.

In another embodiment of the invention the programming means comprises a reading device associated with the store and operative to select the incremental displacement carried out by the displacement means in accordance with the read out from the store. In this case the information for the selection of the appropriate increment in contained directly in the store. The store contains for example a punched tape which for each given cone angle and each stack height and number of laminations contains a row of holes which is sensed and which in each case adjusts the displacement increment applied. Thus for each cycle of the machine the punched tape may therefore be advanced by one hole spacing. The installation may be so constructed that the saddle stock shaft is always advanced by a medium increment and that the punched tape contains no information for the medium increment. Only when a corrective increment step, that is to say a large or small increment, is required does the punched tape contain the corresponding information. The store may however equally well contain punched cards or any other suitable information carriers.

Exemplary embodiments of the invention are described further below with reference to the accompanying drawings, in which:

FIG. 1 illustrates diagrammatically in installation for punching stacks of laminations for conical armature motors, with three punching machines and a common central blank transport device,

FIG. 2 is a diagrammaitcal longitudinal section through a stack of armature and rotor laminations,

FIGS. 3 to 5 illustrate diagrammatically portions of a rotor along a generatrix, which show the profiles of different lamination stacks,

FIG. 6 illustrates a stepping mechanism according to the invention, providing different predetermined, selectable displacement increments,

FIG. 7 is a block circuit diagram of one form of programming means,

FIGS. 8 to 10 illustrate alternative embodiments of stepping mechanisms, and

FIG. 11 illustrates an arrangement of twin magnets which may be used in place of the double cylinder arrangement of FIG. 9.

Referring to FIG. 1, three notching presses 2, 3, 4 and receiving stations 5, 6, 7 for the laminations are disposed around a 6-armed transport spider 1, at the ends of the arms of which there are disposed gripping and holding devices (not shown). In the first station, the receiving station 5, there is disposed a stack 8 of blanks which at the beginning of the machining contains blanks corresponding to a complete stack of laminations, that is to say comprises the stator and rotor laminations of a motor. From the receiving station 5 the transport spider 1 takes the uppermost blank 16 and delivers it to the press 2, in which a punching operation (i.e. one press cycle) is effected in the intervals of time between the intermittent movements of this transport spider. This punching operation consists in punching out in succession stator slots in the appropriate parts of the blank. The transport spider 1 then takes the blank in which the stator slots have been punched and delivers it to the next station, namely the press 3, which cuts a rotor lamination 17 out of the blank 16 by successive cuts, so that a stator ring 18 and the circular rotor lamination 17 are separated from one anoiher. The stator lamination 18 is thus complete and is delivered by the transport spider 1 to the next station, the receiving station 6. The rotor lamination 17 is delivered by the transport spider 1 to the press 4, in which the rotor slots are punched. After the rotor slots have been punched the complete rotor lamination 17 is caried by the transport spider 1 to the receiving station 7, at which the rotor laminations 17 are collected. The respective operations described above take place simultaneously in all the stations on successive blanks. Thus when the first rotor lamination reaches the receiving station 7, the second rotor lamination has reached the press 4, the third stator lamination the receiving station 6, the fourth blank the press 3, the fifth blank the press 2, and the sixth blank is now the uppermost blank 16 and is about to be taken from the stack 8 by the transport spider 1 at the beginning of the next press cycle. Conventional notching presses for producing stator and rotor laminations for electric motors operate in this manner.

In order to enable the stacks of laminations for conical armature motors to be produced it is necessary for the outside diameter of the rotor lamination 17, and consequence also the inside diameter of the stator laminations 18, and the diameters of the two rings of slots to be varied. For this purpose the saddle stock shafts of the presses, which are not illustrated in the drawing and which consist of mandrels on which the blanks 16 are centred and secured against rotation, are adjustable in respect of their radial distance from the tool. These saddle stock shafts are rotated stepwise between successive punching operations, the steps coresponding to the spacing of the slots in each ring of slots. The shafts complete a revolution for each press cycle.

The radial movement of the saddle stock shafts is effected incrementally. If the number of increments is equal to the number of laminaitons in a stack, an ideal generatrix is obtained with the smallest possible steps between successive laminations, as is illustrated in FIG. 3, which shows a stack of rotor laminations 17 before a final operation in which the external contour of the rotor and the corresponding internal contour of the stator are ground down after the laminations have been stacked so as to form a perfectly conical rotor 9 and a cylindrical stator 10 provided with a hollow conical bore.

For each type of motor the height of the stack of laminations is constant and predetermined. Since however thickness of the laminations varies, the number of laminations in each stack is not constant, but may deviate from a mean value by i10%. Using constant displacement increments to obtain the result illustrated in FIG. 3, there would thus be a narrower cone angle in the case of a smaller number of laminations, since fewer feed steps have been carried out by the time the complete stack has been punched, and conversely with a larger number of laminations there would be a more obtuse cone angle, since more feed steps would be made for the same stack height; it is assumed in both cases that the largest diameter rotor laminations were punched first. It is naturally equally possible to start with the smaller diameter rotor laminations and to adjust the feed in such a manner that the diameters of the laminations increase. The important disadvantage which is incurred is that in the first case the final diameter would be larger and in the second case smaller than the desired value, which of course is impermissible. In previously known machines the drive moving the saddle stock shaft therefore occasionally disengaged or caused to move it by two increments in order to limit the deviation of the contour shape of the lamination stack from that desired. For example, the increments were adjusted so that a correct contour would be achieved with those stacks containing the smallest number of laminations, and occasional increments were omitted with stacks containing a larger number of laminations: thus two successive laminations were periodically punched with the same diameter. The resulting generatrix is shown in FIG. 4, where it will be seen that in several cases rotor laminations 11, 12 of the same diameter have been produced in succession, whilst between them in each case there are a certain number of rotor laminations 13 having decreasing diameters. In this manner it is possible to obtain the required cone angle: however substantially more metal removal work is necessary in order to obtain a smooth control surface during the subsequent grinding operation.

FIG. shows diagrammatically the contour of a rotor lamination stack produced by a press in accordance with the invention. Through the controlled selection of different increments it is possible with the ratchet wheel described further on to work with stacks having any number of laminations so as to achieve the desired final diameter, and nevertheless to obtain a relatively slightly stepped contour. In accordance with the deviation of the number of laminations in the stack from the mean number, it is possible in each case to insert suitable corrections during the punching of the laminations forming a stack so the saddle stop shaft is displaced periodically by a larger or smaller increment than normal. The stepped character of the stack contour is thereby reduced.

Referring to FIG. 6, a ratchet Wheel 21, which is mounted on and integral in rotation with a shaft 22 transmitting the rotary movement to a drive displacing the saddle stock shaft is driven by a pawl 23. An arm 24 is pivoted at one end for movement about the shaft 22, this end of the arm 24 being integral with a lever 25 which is provided at its free end with a pivot pin 26 on which the pawl 23 is journalled. Two fluid operated rams 27 and 28 are articulated on the frame of the press being controlled, their piston rods 29 and 30 being connected by pivots 31 and 32 respectively to a connecting link in the form of a rod 33. On the rod 33 there is provided a bearing pin 34 situated closer to the pivot 31 than the pivot 32, the free end of the arm 24 being journalled on the pin 34. When the two rams 27 and 28 are in their unextended positions, the bearing pin 34 assumes the position shown at 35 on the broken line 36 which represents the position of the rod 33 under these circumstances. When the ram 28 is operated, the entire assembly assumes the position illustrated in FIG. 6. Alternate actuation and retraction of the ram 28 therefore moves the bearing pin 34 toand-fro between the position shown and the point 35; in this case therefore a relatively small movement is transmitted through the arm 24 and the lever 25 to the pawl 23 and bring about a correspondingly small angular advance of the ratchet wheel 21. If the ram 28 is not actuated and the lifting cylinder 27 is actuated and retracted again, the bearing pin 34 will move from the point 35 to the point 37 and back, moving the rod 33 to the position shown by the broken line 38 and back again. A medium movement of the arm 24 is therefore produced, which produces in turn a medium angular advance of the ratchet wheel 21. If on the other hand both the rams 27 and 28 are simultaneously actuated and retracted, the bearing pin 34 moves from the point 35 to a point 39 and back, thus moving the rod 33 to the position shown by the broken line 40 and back again. The consequent large movement of the bearing pin 34 results in a corresponding large angular advance of the ratchet wheel 21. In normal operation only the ram 27 is actuated and retracted and thus the saddle stock shaft is displaced by medium increments. Under the control of the programming device, either the ram 28 is occasionally operated simultaneously, whereby a larger increment is obtained, or instead of the ram 27 the ram 28 is operated, whereby a smaller increment is obtained. In this simple manner it is possible to vary the increments by which the saddle stock shaft is displaced simply by selective operation of the two lifting cylinders, which are identical to one another.

However, it is also possible with only one lifting cylinder likewise to obtain small, medium, and large increments. In FIG. 8, a single ram 71 is pivoted on the press frame, its piston rod 72 carrying at its free end a bearing pin 73 on which the arm 24 is journalled and which corresponds to the bearing pin 34 in FIG. 6. On the piston rod 72 is provided a turret 74 which is rotatable relative to the piston rod 72 but is axially immovable thereon, this turret being provided with shoulders 75 which are stepped in the axial direction and which cooperate with a stop 76 fastened to the press frame, A program storage unit 70 controls a stepping motor 68 via a line 69; this stepping motor executes individual forward and reverse steps depending on the pulses fed thereto via line 69, which pulses are delivered by the storage unit 7 0 in correspondence with the program stored therein. The stepping motor 68 has a shaft 67 rotating by corresponding angular steps. A gear (cog) wheel 66 is fixed to the shaft 67, this gear wheel meshing with a gear wheel 65 wedged onto the piston rod 72. Thus, the stepping motor 68 controls the rotary motion of the turret '74. The programming means is operative to rotate the turret 74 and thus select which shoulder is brought to bear against the stop 76 on the operation of the ram 71, whereby the different incremental displacements of the saddle stock shaft are obtained. Instead of the arrangement illustrated there may be provided on the piston rod 72 a coaxially disposed, rigidly fastened rotationally symmetrical stepped disc, the stop 76 being adapted to be moved out to different distances in order to select the required increment by engaging different steps on the stepped disc.

A gear wheel 110 is atached to the shaft 22 for rotation therewith, this gear wheel participating in the angular steps of the shaft 22. The gear wheel 110 meshes with a gear rack 111, the latter moving in its longitudinal direction depending on the size and direction of the angular steps of the gear wheel 110. At one end of the gear rack 111, a support 112 is mounted which is guided to be able to reciprocate in the longitudinal direction of the gear rack 111 in guides, the latter not being shown. A ramrod shaft 113 is rotatably mounted in the support 112, this shaft being rotated by one angular step about its longitudinal axis after each notching step, this angular step corresponding to the slot spacing of the blank 16 to be punched. The rotation of the ramrod shaft 113 is coupled with the upward and downward movement of a ram 114, so that the ramrod shaft executes a rotary step always when the ram 114 is in the position indicated in FIG. 8. The ram 114 carries an upper tool 115 cooperating with a lower tool 1167 Upon the downward movement of the ram 114, the upper tool 115 penetrates through the blank 16 into the lower tool 116 and, during this procedure, punches a section metal out of the blank 16 which corresponds to the notch shape. The ram 114 is supported in a machine frame 117 which also exhibits a table 118 on which the lower tool 116 is attached. The spacing of the machine frame 117 from the shaft 22 is fixed. In FIG. 8, parts 112 through 118 are illustrated schematically on a scale which is greatly changed as compared to the other parts' It is to be understood that the components 65 through 76 and 21 through 26 are provided within the machine frame 117.

In the embodiment illustrated in FIG. 9 a double ram 81 is utilized having two separate cylinder chambers 82 and 83 in which pistons 84 and 85 are guided. The cylinder 82 is supplied with pressure medium through pipes 86 and 87 and the cylinder 83 is provided with pressure medium through pipes 88 and 89. A piston rod 90 fast to the piston 84 is pivoted to the press frame, whilst a piston rod 91 fast to the piston 85 carries at its free end the bearing pin 73 on which the arm 24 is journalled. By selectively connecting the pipes 86, 87, 88 and 89 to a supply of pressurized fluid the three different increments can be selected. The two cylinders 82 and 83 are of different lengths. The rest position of the pin 73 is obtained when the pipes 86 and 89 are under pressure, that is to say when the pistons are at their nearest approach to each other. If for example the cylinder 82 is slightly shorter than the cylinder 83, a small increment is obtained by switching over the pressure from the pipe 86 to the pipe 87 while the pipe 89 remains under pressure. The ram 81 is thereby displaced by the stroke of the piston 84 and carries with it the piston 85 with the piston rod 91. If, starting again from the rest position, a medium increment is to be obtained, the pipe 86 remains under pressure and pressure is applied to the pipe 88 instead of to the pipe 89, whereupon the piston 85 performs a stroke movement with the ram 81 stationary relative to the press frame. A medium increment is then obtained, because the stroke of the piston 85 is longer than that of the piston 84. In order to achieve a large increment, the pipes 87 and 88 are placed under pressure, whereupon both pistons move into their outer end positions. Instead of using the arrangement of FIG. 9, an arrangement of the type illustrated in FIG. is also possible, in which an outer cylinder 93 is pivoted to the press frame and encloses a chamber 94 which is provided with two pipes 95 and 96. The cylinder 93 serves as guide for another cylinder 97, which in its interior is provided with a chamber 98 in which a piston 99 is guided. The piston 99 is provided with a piston rod 100 at the free end of which is the pin 73. The chamber 98 is provided with two inlet pipes 101 and 102, whilst the stroke of the piston 99 is shorter than that of cylinder 97 in the cylindrical space 94. In the rest position pressure is applied to the pipes 96 and 101, so that the cylinder 97 and the piston 99 are situated in the positions in which they are closest to the pivoted end of the cylinder 93. In order to obtain a small increment the pipe 101 is relieved of load and pressure is applied to the pipe 102, whereupon the piston 99 performs a short stroke. If on the other hand a medium increment is to be obtained, the pipe 96 is instead relieved of load and the pipe 95 subjected to pressure, whereupon the cylinder 97 performs a stroke while the piston 99 remains stationary relative to the cylinder 97. When a large increment is to be obtained, the pipes 95 and 102 are placed under pressure and the pipes 96 and 101 relieved of load.

In the programming device illustrated in FIG. 7, a decade switch 41 operates a preselector 42 the position of which is shown by an indicator 43. The preselector 42 controls an input control unit 44 which interrogates a reader 45, for example a punched tape reader, and feeds the signals thus received to a buffer store 46-, which in turn acts on the preselecting device incorporated in and determining the length of the counting cycle of a ring counter 47. A lead line 60 with a switch 61 connected in series therewith is provided at the preselector ring counter 47, this line leading to a current supply line, not shown. A second lead line 62 extends directly from the current supply unit, not shown, to the preselector ring counter 47. All remaining units illustrated in FIG. 7 are supplied with electric current from the preselector ring counter 47. The ring counter 47 is in addition provided with a manual input 48, by which preselection can also be effected. Moreover, the ring counter 47 has an indicator unit 49 which indicates the counter reading. The ring counter 47 is supplied with pulses by a pulse generator comprising a signal generator 51 which by way of an intermediate counter 52 acting as gate circuit supplies a predetermined number of pulses to the preselector ring counter 47 for each press cycle. The ring counter 47 is so constructed that every time a counting cycle has been completed, that is to say when the number of pulses fed in is equal to the preselected cycle length so that the indicator unit 49 indicates zero, it recommences counting at the number corresponding to the cycle length originally preselected. The fly back period is selected so no pulses are lost during said period. Every time the preselector counter 47 passes through its zero position it transmits a signal to an evaluation circuit 53, which shapes and amplifies the signal and passes it on to a processing and amplifying stage 54, from which the signal is fed to a ram control unit 55 controlling solenoid valves 56, 57 by which the pressure medium supply pipes to the rams 27, 28 (FIG. 6) are opened or closed. Two liner, namely a plus line 58 and a minus line 59, are connected to the unit 55 and-although this is not illustrated in the drawingare also connected to the manual input 48 and to the buffer store 46 respectively. Since the press is arranged always to perform a medium incremental displacement of the saddle stock shaft between each cycle when no correction signal is supplied by the ring counter 47, and, as already stated, for each stack of laminations only either larger increments or smaller increments are periodically necessary for correction purposes, one of the two lines 58 and 59 is also operated by the hand input 48 or the buffer store 46 respectively, and the ram control unit 55 is so constructed that in all cases only the solenoid valve 56 supplying the ram 27 is normally opened and closed at each press cycle, whereby a normal increment of displacement is applied to the saddle stock shaft. If a signal is fed to the line 58, the plus line, the unit 55 will ensure, when a signal arrives from the stage 54, that on the next feed step the ram 28 will be operated instead of the ram 27, that is to say the solenoid valve 57 will be operated instead of the solenoid valve 56, so that a larger increment will be obtained. If on the other hand a signal is applied to the line 59 and another signal comes from the stage 54, the unit 55 will open not only the valve 56 but also the valve '57, so that both rams 27 and :28 will be operated and a larger increment will be applied.

A numerical example is given below. With a given size of lamination stack containing an average of 120 laminations, the number of laminations may vary by :10%, that is to say the minimum will be 108 laminations per stack and the maximum 132 laminations per stack. In this example the number of teeth of the ratchet wheel 121 amounts to 149; the total displacement of the saddle stock shaft during the machining of a stack of liminations amounts to 12 mm. For each machine cycle the intermediate counter 52 transmits either 10 or pulses to the ring counter 47. The count cycle preselected for the ring counter 47 is adjusted, either by hand by means of the hand input 48 or by means of the store operated by the decade switch 41, and depends on the actual number of laminations. The operator of the press or presses can read this count cycle length from a table of the type given below as an example. The sign of the cycle length indicates which of the two lines 58 and 59 is to receive a signal.

1 Standard lamination.

If the ring counter 47 is not adjusted by means of the manual input 48 but by means of the buffer store 46,

it is sufiicient simply to select the number of laminations by means of the decade switch 41, the sign of the counter cycle length being contained in the store, by which it is then transmitted, to the two lines 58 or 59 so as to set the unit 55. If for example the number of laminations is 116, the counter adjustment will be 913 if 100 pulses per machine cycle are fed to the ring counter, or 91 if only pulses per press cycle are fed to the counter. In addition, a signal is applied to the line 59, the minus line. Assuming that 100 pulses are utilized per machine cycle, 100 pulses are now counted by the ring counter, so that at the end of each series of 100 pulses the count has moved downwards by 100 and after 9 press cycles the indication given by the indicator 49 is 13. On the next series of pulses the zero position is passed through and in known manner the counter 47 transmits an output pulse which, after shaping and processing, reaches the unit and together with the signal on the line 59 has the effect that both control valves 56 and 57 and thus boh rams 27 and 28 are operated, whereby a larger increment of displacement of the saddle stock shaft is produced and thus the profile of the stack of laminations is again brought closer to the desired profile line. After zero has been reached, upon which the ring counter 47 transmits the output signal, the counter flies back to the beginning of the count cycle (of 913 counts) and now counts the 87 pulses that remain of the series of of which 13 pulses were counted in the first count cycle, so that the count stands at 826 before the next series of pulses is received.

In the arrangement of FIG. 1 which includes three presses, it is possible for each press to have an independent control system, these systems having operating cycles olfset in respect of each other to an amount appropriate to the number of press cycles by which the presses themselves are offset relative to one another. It is however more convenient to provide only one programming means and to control all three presses simultaneously. Since the increments by which the saddle stock shafts are advanced are of only a few h-undredths of a millimetre, there is consequently only a slight displacement of the rings of slots in relation to the surface of the cone, which will normally be well within permissible tolerances.

Since the stack height and cone angle are predetermined for any given type of motor it is possible for a fixed programme to be worked out for each of the possible numbers of laminations, this programme being fed into a store which is read out, the reading device directly controlling for example the two rams in the embodiment of FIG. 6, and/or for the direct control of the turret 74 in FIG. 8.

In FIG. 11, an arrangement with twin magnets, corresponding in its mode of operation to the doubie cylinder 81, is schematically illustrated. A lifting rod is rotatably supported at one end at a bearing block 121 fixedly mounted at the machine. At its other end, the lifting rod 120 carries a magnet armature 122. A further lifting rod 123 is pivotably attached to the bearing pin 73 of the connecting member 24; this lifting rod carries a magnet armature 124 at its other end. The magnet armatures 122 and 124 are displaceably supported in a housing 125 of a twin magnet 126. The magnet armature 122 plunges, for this purpose, in a bore 127 starting at the front face of the housing 125 and extending axially into the housing 125. A corresponding bore 128 emanates from the opposite front face of the housing 125; the magnet armature 124 is guided in this latter bore in a longitudinally displaceable manner. The bores terminate in the housing 125 before reaching each other; they are arranged coaxially with respect to each other. The bore 127 is shorter than the bore 128. The bore 127 is surrounded by two windings 129 and 130 disposed in series in the axial direction of the bore 127, respectively one pair of lead lines 131 and 132 extending to these windings. If the winding 129 is supplied with current via lines 131 from the control device, the magnet armature 122 is moved in the illustrated position relatively to the housing 125 andis maintained in this position. Since the magnet armature 122 cannot change its distance with respect to the hearing block 121, he housing 125 is move accordingly. In the same manner, the bore 128 is surrounded by two windings 133 and 134 disposed in series in the axial direction and to which respectively one pair of lead lines 135 and 136 extend. If current is applied from the control device through the lead lines 135 and thus through the winding 133, the magnet armature 124 assumes the position illustrated in the drawing. If, now, for example, the winding 129 is rendered currentless and current is applied to the winding 130, thus exciting this winding, the housing 125 moves in the direction toward the hearing block 121 until the magnet 122 is within the range in the interior of the winding 130. Since the winding 133 remains in the excited state, the magnet armature 124 does not execute a relative movement with respect to the housing 125, thus moving in the same manner as the housing 125. In the same way, it is also possible to move the magnet armature 124 into the zone of the winding 134 by de-ener-gizing the winding 133 and energizing the winding 134. These movements are transmitted, analogously to the arrangement of FIG. 9, to the connecting member 24, resulting in corresponding angular step motions of the ratchet wheel 21 and thus of the shaft 22.

It is obvious that the invention is not restricted to the specific embodiments illustrated, but that variations thereof are possible without departing from the scope of the invention as defined in the appended claims.

What we claim is:

1. A notching press for producing stacks of iaminations for conical armature motors, comprising a saddle stock shaft adapted to receive a sheet metal blank, a punching tool displaced radially relative to the axis of the saddle stock shaft, and means providing incremental radial displacement of the saddle stock shaft relative to the tool, wherein the incremental displacement means is operable to produce any one of a plurality of different displacement increments and a programming device is provided operative to determine a sequence in which said incre mental displacements are selected, the programming device being programmable in dependence on the number of blanks required to form a lamination stack of the required dimensions.

2. A notching press according to claim 1, wherein the programming device compries a store containing a plurality of programmes selectively operable to control the programming device.

3. A notching press according to claim 1, wherein the displacement means is a stepping mechanism operative to control the radial displacement of the tool relative to the saddle stock shaft.

4. A notching press according to claim 3, wherein the stepping mechanism comprises a ratchet wheel in driving connection with a mechanism operative to shift the saddle stock shaft relative to the tool, and a pawl located for movement relative to the wheel whereby to advance the latter step by step.

5. A notching press according to claim 4, wherein the pawl is drivingly connected to a link pivotally connected, at points spaced from each other and the point of connection to the drive of the pawl, to the movable elements of two telescopic actuators, and the programming device is operative selectively to control the actuators for simultaneous or alternative operation.

6. A notching press according to claim 5, wherein the actuators are soienoids.

7. A notching press according to claim 5, wherein the actuators are fluid operated rams.

8. A notching press according to claim 5, wherein the spacing of the connection points between the link and the actuators and the drive to the pawl is such that the effective lever arm formed by the link in relation to the pawl drive is greater relative to one actuator than relative to the other.

9. A notching press according to claim 1, wherein the programing means comprises a ring counter having a counting cycle of preselectable length and producing an output signal on completion of each counting cycle, means generating a given number of pulses for each cycle of the press and applying them to the ring counter, and means operative to select a ditferent displacement increment to be carried out by the displacement means on receipt of an output signal from the ring counter.

10. A notching press according to claim 9, wherein the pulse generator comprises a signal generator, a counter set to count a preselected number of cycles from the signal generator in response to each cycle of the press, and a gate circuit cutting off the output of the signal generator in response to said counter completing its count.

11. A notching press according to claim 9', wherein the length of the count cycle of the ring counter is manually adjustable.

12. A notching press according to claim 9, wherein a programme store having a reading device is provided, the output of the reading device being applied to means controlling the length of the count cycle of the ring counter.

13. A notching press according to claim 1, wherein the programming device is a Wheel drive stepwise in synchronism with the press, and means are provided transmitting a signal in response to the wheel reaching a predetermined angular position.

14. A notching press according to claim 13, wherein the signal transmitting means comprises a switch in series with electrically operated means operative to select the displacement increment carried out by the displacement means.

15. A notching press according to claim 13, wherein the wheel is a ratchet wheel associated with a variable stroke pawl driven from the press drive.

16. A notching press according to claim 2, comprising a reading device associated with the store and operative to select the incremental displacement carried out by the displacement means in accordance with the read out from the store.

References Cited UNITED STATES PATENTS 3,460,415 8/1969 Philipp 83-267 X 2,433,117 12/1947 Hallander 83-267 X 2,363,208 11/1944 Solzer 83240 X JAMES M. MEISTER, Primary Examiner US. Cl. X.R. 

